When configuring a guest network in your organization, you limit the access. Most probably you’ll only allow certain popular services such as (http, https) to the outside world and block all incoming traffic into your network.

That is guest network can not access private internal network.

One thing to keep in mind when assigning the network details, IP, gateway, DNS, etc. Is assign an external DNS to guest network clients.

They won’t have a problem as long as they are accessing sites and services outside your network but once they try to access anything within your network, there might be a problem.

If they are using your internal DNS to resolve names, they’ll have a problem when accessing for example your homepage, email page, since the internal DNS will resolve it to the internal IP and your firewall settings doesn’t allow guest users access to the internal network.

Where as, if you assign an external DNS, it’ll resolve to the public IP, so they’ll access your published sites and services, like all other outside users, then you won’t have a problem. And that will save you the headache of configuring the firewall to allow guest users access to published sites and services via internal IP.

Each network has their own setup and configuration, but the outcome is the same.